犊牛腹泻大肠杆菌的分离鉴定及耐药性分析

为确定引起湘西北地区某肉牛养殖场犊牛腹泻发生的致病菌种类并分析其耐药性,采用常规培养、革兰染色镜检和生化试验等方法对致病菌进行分离鉴定,利用药物纸片琼脂扩散法(Kirby-Bauer)对分离菌进行药敏试验。结果表明,引起犊牛腹泻的主要致病菌为大肠杆菌;临床分离的大肠杆菌对头孢哌酮、头孢唑林、米诺环素、头孢曲松4种抗生素敏感;对头孢呋辛和头孢他啶2种抗生素中度敏感;对头孢氨苄、哌拉西林、红霉素、万古霉素、强力霉素、青霉素、氨苄西林、羧苄西林、麦迪霉素、环丙沙星、链霉素、丁胺卡那霉素、头孢拉定、庆大霉素、卡那霉素、苯唑西林、复方新诺明、诺氟沙星、奥复酸、四环素、多西环素、林可霉素22种抗菌药物产生耐药性。分离出的大肠杆菌对多种抗菌药物产生耐药性,研究结果为养殖场科学诊断和治疗犊牛腹泻提供了有效依据。

Isolation,Identification and Antimicrobial Susceptibility Test of Escherichia coli Isolates Associated with Calf Diarrhea

This study aimed to determine the pathogenic bacteria causing the calf diarrhea in a beef cattle farm in northwestern Hunan Province, and to characterize their antimicrobial resistance profile. The pathogenic bacterial strains were isolated and identified by using routine culture method, Gram's stain method, microscopic examination and biochemical reaction tests. Antimicrobial susceptibility test of the isolates was performed by Kirby-Bauer disk diffusion method. The results showed that the dominant causative agents associated with the calf diarrhea in this beef cattle farm were identified as Escherichia coli(E. coli); the E. coli clinical isolates were sensitive to cefoperazone, cefazolin, minocycline and ceftriaxone, moderately sensitive to cefuroxime and ceftazidime, and resistant to 22 kinds of antimicrobial agents, including cephalexin, piperacillin, erythromycin, vancomycin, doxycycline, etc. The isolated E. coli strains exhibited resistance to various antibacterial drugs, and our results provided an effective basis for scientific diagnosis and treatment of calf diarrhea.